Metal scrap reclamation system

ABSTRACT

An improved method of melting metal scrap in a molten melting media is disclosed. The method comprises the steps of providing a body of molten melting media in a housing having an upper portion and a lower portion, the lower portion having a generally cylindrical wall section. A supply of metal scrap is added to the housing and a supply of molten melting media is introduced to the upper portion of the housing. Melting of the metal scrap is initiated by ingesting it and molten melting media downwardly in the housing by action of an impeller positioned in the lower portion, the impeller having a flat ring member having an opening in the center thereof and having blades extending from said ring member to a substantially circular disc member. The scrap and melting media enters the opening in the ring member in an axial direction and is propelled therefrom in a radial direction by use of the blades. The impeller is positioned in the cylindrical wall section such that at least the ring member cooperates therewith to move the scrap and melting media from the upper portion through said impeller while substantially avoiding recirculation of the molten melting media within the housing to the upper portion.

This is a division of application Ser. No. 573,115, filed Jan. 23, 1984,now U.S. Pat. No. 4,486,228, which in turn is a continuation ofapplication Ser. No. 475,310, filed Mar. 14, 1983, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to an improved scrap reclamation system and inparticular to a method and apparatus for quickly and efficiently meltingmetal scrap in a recirculating melting system.

Increased effort is being placed on finding cheaper methods to recyclemetal scrap, particularly in the light metals field. This effort isbeing expended because of the national and international concern overdepletion of raw material sources for these metals.

Recycling systems for metal scrap are normally required to be at leastcompetitive with established manufacturing systems for producing suchmetal. To be competitive, such recycling systems must be efficient whichcan often require that they be designed to reclaim certain or specifickinds of metal scrap. With respect to the kinds of metal scrapencountered in the light metals field, particularly aluminum, it shouldbe observed that it can range from scrap generated very early in themanufacturing process to that resulting from used products, e.g. metalcontainers. Scrap generated early in the manufacturing of aluminum, forexample, is scalping chips. These chips result from preparing thesurface of an aluminum ingot for rolling or cladding or some suchpurpose when often large irregularities are removed. Chips removed atthis time can constitute as much as 6% of the total metal in the ingotand, therefore, obviously can amount to a considerable amount of metalwhich can be recycled. Scrap typical of used metal containers which canbe beneficial to recycle is metal beverage cans and the like. Recyclingsuch cans serves to conserve resources and also to provide a cleanerenvironment.

These two types of scrap are often considered to present differentproblems from the standpoint of reclamation. For example, container orcan scrap normally comprises bits and pieces of metal which can range insize from relatively small particles to crushed cans. Often, the canshave holes pierced in them for purposes of delacquering using solvents.The pierced holes, while aiding the flow of solvent through the mass ofcans, result in jagged edges which, together with the generallynon-uniform shapes and sizes of crushed cans, make this scrap relativelynon-flowable. Furthermore, such scrap tends to be rather buoyant withrespect to the melting media, requiring special equipment to forciblysubmerge it. A particular type of equipment for handling this type ofscrap is disclosed in U.S. Pat. No. 3,873,305 where a rotating wedgeforcibly submerges this type of scrap into the melting media. In thesystem described in this patent, additional equipment is required torecirculate the molten melting media.

U.S. Pat. No. 4,128,415 illustrates another system for reclaiming scrapwherein the melting media is drawn up into a bay where a metal scrap ismelted. Further, U.S. Pat. No. 3,997,336 discloses a system wheremelting media and metal scrap are introduced into a bay and the scrap isforcibly submerged using an axial flow impeller.

With respect to the scalping chips, or scrap which may be characterizedas flowable, for example, such as filings and cuttings or even largepieces, these can present difficulty in submerging as does theabove-mentioned container scrap. Nevertheless, it is imperative thatsuch flowable scrap be melted and reclaimed in the most efficient mannerin order to provide an incentive to operate a remelting system as asource of metal, as compared to the established manufacturing system forproducing such metal.

With highly oxidizable metals, such a aluminum, out of which theaforementioned containers and beverage cans are often made, it isimportant to provide a remelting system which provides maximum heattransfer for efficient melting. Also, it is important that the metalscrap be submerged with minimum turbulence at the melting media surfacein order to mimimize oxidation of the molten metal. Oxidation leads toskim formation, a problem inherent in most systems reclaiming highlyoxidizable metals such as aluminum.

The skim referred to includes the metal oxide, e.g. Al₂ O₃, and moltenmetal which becomes entrained in such oxide. Skim is undesirable and,therefore, should be minimized not only because of the molten metal lostto it, but also because it can cause problems by acting as an insulatorin the heating bay. That is, when combustion units discharging theirheat on the surface of the molten media in the heating bay are used,skim floating on the surface thereof makes it difficult to heat themolten media. Also, such floating skim by rejecting heat can seriouslyshorten the useful life of the equipment by causing it to overheat.

The present invention provides a highly efficient method ofrecirculating molten melting media and for reclaiming metal scrap in arecirculating melting system. The method is suitable for reclaimingeither flowable or non-flowable scrap of the type referred to above.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a recirculating systemfor melting metal scrap.

Another object of the invention is to provide a melting system foraluminum scrap.

Yet another object of the invention is to provide a melting system formetal scrap wherein the metal scrap is ingested through an impellerhaving axial flow thereinto and radial flow therefrom.

And yet another object of the present invention is to provide means forrecirculating molten metal or molten melting media in a system suitablefor melting metal scrap.

These and other objects will become apparent from a reading of thedisclosure and claims and an inspection of the claims appended hereto.

An improved method of melting metal scrap in a molten melting mediacomprises providing a body of molten melting media in a housing havingan upper portion and a lower portion, the lower portion being suited tocooperate with an impeller to pump molten melting media through thehousing. A supply of metal scrap may be added to the upper portion ofthe housing. A supply of molten melting media is introduced to the upperportion of the housing. Melting of the metal scrap can be initiated oraccomplished by ingesting it and molten melting media downwardly in saidhousing by action of an impeller positioned in the lower portion, theimpeller having a flat ring member having an opening in the centerthereof and having blades extending from the ring member to asubstantially circular disc member. The melting media enters the openingin the ring member in an axial direction and is propelled therefrom in aradial direction by use of said blades. The impeller is positioned inthe lower portion such that at least said ring member cooperates withthe cylindrical wall section or other wall section in the housing tomove melting media from the upper portion through said impeller whilesubstantially avoiding recirculation of the molten melting media withinthe housing to the upper portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a general schematic of a circulatorysystem in accordance with the present invention.

FIG. 2 is a plan view of a hot chamber and cold chamber in therecirculating melting system.

FIG. 3 is an elevational view in cross-section illustrating a pumpingand scrap charging bay in accordance with the invention.

FIG. 4 is an elevational view in cross section through the pumping bayshowing molten entrance and exit channels.

FIG. 5 is a top view of a pumping bay in accordance with the invention.

FIG. 6 is a pictorial view of the impeller in FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now more specifically to FIG. 1, there is shown a schematic ofa recirculating scrap melting system 30 in accordance with the presentinvention. In the recirculating melting system, melting media iscirculated from heating bay or hot chamber 32 via conduit 34 to pumpingand scrap charging bay 36. In bay 36, molten melting media, e.g. moltenmetal or molten aluminum, is drawn thereinto and scrap can be ingestedthereinto by action of a pump impeller located in the bay. The moltenmelting media and ingested scrap are discharged or propelled from thebay into a skim bay 40, for example, for treatment or removal of skim ordross before being discharged from the system or passed into a holdingfurnace 42. It will be appreciated that molten metal can be removed fromthe system at a rate commensurate with the rate at which scrap is added.

The melting media, such as molten aluminum, can be heated by use ofburners such as combustion units located in hot bay 32 or electricalheaters such as induction or resistance heaters immersed in the moltenmetal.

The melting media can be molten material of similar composition to themetal charge or it may be a molten salt. If a molten salt is used, asalt-metal separation would normally be necessary to facilitate theremoval of the melted metal. When molten aluminum is the melting media,a typical temperature leaving the heating bay 32 can be about 1400° F.although this temperature can range from 1325° to 1475° F., but with ahigher temperature there is a greater tendency to form skim. A typicaltemperature re-entering heating bay 32 can be about 1250° to 1300° F. oreven slightly lower without fear of solidification. This provides abouta 100° F. temperature drop across the melting bay to provide heat tomelt the charge. However, it should be noted that this temperature dropdepends somewhat on charge rate and circulation rates. For example, thecharge rates and circulation rates can be such that the temperature dropwould only be 20° F.

Referring now to FIG. 2, there is shown another schematic of arecirculating system in accordance with the present invention. In thisembodiment, melting media is circulated from hot chamber 50 via line 52by action of an impeller in pump bay 54. Melting media can be dischargedinto a skim removal bay 56 and there via line 58 to a cold chamber 60where scrap to be melted can be charged. Molten metal can be removed at62 at a rate commensurate with the rate of scrap charging, if desired.Cold chamber 60 can be separated from hot chamber 50 by a wall 64 (seeFIG. 3). The wall can have an opening 66 therein to pass molten metalfrom the cold bay to the hot bay. If the scrap is of the type which hascoatings such as oil thereon, the fumes resulting therefrom can pass orbe removed through opening 68 to the hot bay from which they can beremoved from the system through channel 70 for treating or being burnedtherein. Hot chamber may be heated as noted above.

Referring now to FIG. 4, there is shown an elevational cross-sectionalview of bay 36 (FIG. 1) which permits charging of metal scrap 72thereinto which is ingested into molten melting media 74. That is,impeller 73 serves to circulate the molten melting media from the hotbay through the pumping and scrap charging bay to a skim removal bay andhence to the hot bay or a holding furnace. Impeller 73 has aconfiguration which requires the molten metal and scrap to be melted tobe ingested downwardly in an axial direction into the impeller andexpelled or propelled therefrom radially. Having the melting media andcharge change direction in the impeller can result in greater meltingefficiency. Thus, in FIG. 4, it will be seen that molten melting mediais drawn from bay 32 through bay 36 and propelled through opening 88into skim bay 40.

In order that the molten melting media be circulated efficiently, it isimportant that impeller 73 be positioned precisely in lower portion 76of bay 36. That is, in order that impeller 73 draws the molten meltingmedia downwardly in an axial direction and moves it into skim bay 40,the melting media, after having passed through impeller 73, cannot bepermitted to recirculate into upper portion 78 of the bay. It will beunderstood that to permit substantial amounts of melting media to returnfrom lower portion 76 to the upper portion 78 results in the pumping orrecirculating action being adversely affected. By a "substantial amount"is meant an amount greater than may unavoidably escape through or aroundthe fitting between the impeller and the wall section 80 in lowerportion 76. It will be understood that if the impeller is merely placedin an open bay, it will function as a mixer rather than circulatingmechanism.

Lower housing at sidewall 80 can be substantially circular to fit andcooperate with impeller 73 to pump molten melting media. However,sidewall 80 may be shaped to provide an opening other than circularwhich can be shaped to cooperate with impeller 73 positioned therein tominimize the amount of molten metal escaping to the upper portion.

In FIG. 4, it will be seen that impeller 73 is carried on a shaft 82.Further, it will be observed that impeller 73 is fitted into lowerportion 76 with a tolerance being provided at least between lowerhousing 76 at side wall 80 and the top of the impeller to prevent orminimize the amount of molten melting media that may escapetherebetween. Thus, in operation, impeller 73, as well as recirculatingmelting media, continuously depletes and replenishes the melting mediain bay 36, the depletion rate being commensurate with the rate at whichmelting media and scrap are added to the bay.

An impeller and its position in lower portion 76, which has been foundto be suitable for this operation, is shown in FIGS. 4, 5 and 6.Further, in FIG. 4, it will be observed that melting media can beintroduced to bay 36 through an opening 86, which for purposes of thepresent invention may be placed below level 84 of the melting media butabove impeller 73. In addition, for purposes of expelling materialradially from impeller 73, a channel or opening 88 must be provided inlower portion 76, as shown in FIG. 4, for example.

From FIGS. 4 and 6, it will be noted that impeller 73 has a top, flatcircular ring member 90 and a flat circular disc member 92. Between ringmember 90 and disc member 92, blades 94 extend in a generally radialdirection from a central hub 96. Hub 96 provides means by which theimpeller may be joined or carried on shaft 82. With the shaft joined toimpeller 73, ring 90 provides or defines openings 98 with blades 94through which the molten metal or melting media is drawn and from whichmolten material is expelled radially into opening 88.

It will be understood that means may be added to the top ring 90 topermit it to cooperate with sidewall 80 to restrict the amount ofmelting media which may recirculate to the upper portion of the housing.That is, it will be understood that when ring member 90, for example,overlaps sidewall 80, the sidewall overlap may be circular or some othershape which does not permit recirculation of the molten material in thehousing.

In a preferred aspect of the invention, wall 87 of bay 36 may have aconfiguration, as shown in FIG. 5, to facilitate flow of molten meltingmedia through impeller 73. That is, bay 36 is arranged to provide aspiral shaped flow pattern to molten metal entering the upper portionand leaving the lower portion. Thus, in FIG. 5 molten metal enters theupper portion along channel 100 which has sides 101 and 102. It will benoted that impeller 73 is placed in the lower portion 76 and is placedwithin circular wall section 80. Wall 101 continues in a circularpattern which may be described as one which has a decreasing radiusuntil it meets side 102. This configuration is useful in itseffectiveness in directing molten melting media through the impeller.When the melting media passes through the impeller, it is preferred thata channel or conduit be used that opens into an exit 104 having sides105 and 106 with side 106 which is generally circular and may bedescribed as a circle having an increasing diameter until it becomesmore or less parallel to side 105.

In operation, the present system is capable of pumping as much as onemillion pounds per hour of molten metal or melting media at an rpm of100 to 140. This rate of pumping may be achieved with an impeller havingabout a 20 inch diameter and having blades approximately six inches inheight. The band of ring member 90 may be about five inches in width.

In the present system, materials of construction of bay 36 can be anymaterial suitably resistant to erosion or corrosion by molten aluminumor molten salts. Such materials include silicon carbide or any otherrefractory normally used with molten aluminum. With respect to theimpeller, since dimensions can be relatively imprecise when compared topumps normally used to pump molten metals, e.g. no seals, etc., theimpeller and shaft can be cast. Alternatively, if the fabricatingmaterial is graphite, the impeller assembly can be machined. Preferably,the impeller 73 is fabricated from a refractory material comprising azinc borosilicate frit. A particularly suitable zinc borosilicate fritis described in U.S. Pat. No. 4,088,502, hereby incorporated byreference.

While the invention has been described in terms of preferredembodiments, the claims appended hereto are intended to encompass otherembodiments which fall within the spirit of the invention.

What is claimed is:
 1. A recirculating system for ingestion of metalscrap into a molten melting media comprising:(a) a heating baycontaining the molten melting media; (b) a scrap charging bay havingupper and lower portions wherein metal scrap is charged into the upperportions of the bay and ingested into said melting media, the scrapcharging bay connected to said heating bay to permit molten meltingmedia to be circulated from the heating bay through the scrap chargingbay and back to the heating bay; and (c) an impeller positioned in thescrap charging bay for purposes of ingesting said metal scrap into themolten metal media;(i) the impeller having a top member and spacedtherefrom a base member, the top member provided with an openingtherein, said impeller having blades positioned between said top memberand base member, the blades extending in a generally radial direction,(ii) the impeller adapted to draw scrap values and melting media throughthe opening in said top member in a downward direction on rotationthereof and to propel said scrap values and melting media therefrom in agenerally radial direction by use of said blades, the impellerpositioned so as to move the scrap values and melting media from saidupper portions through said impeller and out into lower portions of thecharging bay.
 2. The recirculating system in accordance with claim 1wherein said top member is a substantially flat ring member having asubstantially circular opening therein.
 3. The recirculating system inaccordance with claim 1 wherein said base member is a circular member.4. The recirculating system in accordance with claim 1 wherein said basemember has a centrally located hub thereon and wherein said bladesextend from said hub in a generally radial direction.
 5. Therecirculating system in accordance with claim 4 wherein said blades areeccentric to said hub.
 6. The recirculating system in accordance withclaim 4 wherein said blades are curved backwardly from the direction ofrotation and extend from said hub towards the circumference of said basemember.
 7. The recirculating system in accordance with claim 1 whereinsaid impeller has a central hub and said blades extend outwardly fromsaid hub but eccentric to its axis in the direction of rotation andcurve backwardly from the direction of rotation.
 8. The recirculatingsystem in accordance with claim 1 wherein the lower portion has at leasta region thereof having a generally cylindrical wall section.
 9. Therecirculating system in accordance with claim 1 wherein the charging bayhas a generally spiral shaped configuration extending from the upperportions to the lower portions to facilitate the ingestion of scrap intothe melting media and the flowing of scrap values and melting mediathrough the charging bay.
 10. A recirculating system for ingestion ofmetal scrap into a molten melting media comprising:(a) a heating baycontaining the molten metal media; (b) a scrap charging bay having upperand lower portions wherein metal scrap is charged into the upperportions of the bay and ingested into said melting media, the scrapcharging bay connected to said heating bay to permit molten meltingmedia to be circulated from the heating bay through the scrap chargingbay and back to the heating bay; (c) an impeller positioned in the scrapcharging bay for purposes of ingesting said metal scrap into the moltenmelting media, the impeller having a top member and a base member, thetop member provided with an opening therein and having blades affixedlypositioned between said top member and base member, the blades extendingin a generally radial direction; (d) means for rotating said impeller todraw downwardly scrap values and melting media through the opening insaid top member and to propel said scrap values and melting mediatherefrom in a generally radial direction to thereby move said scrapvalues and melting media from said upper portions to said lower portionsof said bay; and (e) means for avoiding substantial recirculation ofmelting media within said bay.
 11. A recirculating system for ingestionof metal scrap into a molten melting media comprising:(a) a heating baycontaining the molten melting media; (b) a scrap charging bay havingupper and lower portions wherein metal scrap is charged into the upperportions of the bay and ingested into said melting media, the scrapcharging bay connected to said heating bay to permit molten meltingmedia to be circulated from the heating bay through the scrap chargingbay and back to the heating bay; (c) an impeller positioned in the scrapcharging bay for purposes of ingesting said metal scrap into the moltenmelting media, the impeller having a flat ring member and a circularbase member having a central hub, the flat ring member connected to thecircular base member by blades which extend radially from said hub, theimpeller carried on a shaft extending through the ring member; (d) meansfor rotating said impeller to draw downwardly scrap values and meltingmedia through the opening in said ring member and to propel said scrapvalues and melting media therefrom in a generally radial direction tothereby move said scrap values and melting media from said upperportions to said lower portions of said bay; and (e) means for retardingrecirculation of melting media within said bay.
 12. A recirculatingsystem for melting metal scrap in a molten melting media comprising:(a)a heating bay containing the molten melting media; (b) a scrap chargingbay containing molten melting media and having upper and lower portionsand connected to said heating bay to permit molten melting media to becirculated from the heating bay through the charging bay and back to theheating bay; (c) an impeller positioned in the lower portion of thecharging bay for ingesting metal scrap into the molten melting media,said impeller having a substantially vertical axis of rotation andincluding a substantially horizontally disposed ring member with anopening near the center thereof, a substantially horizontally disposeddisc spaced below said ring, and blades extending outwardly from theaxis of the impeller between said ring member and said disc member; and(d) means for rotating said impeller to draw molten media and scrapdownwardly through the opening in the ring member of said impeller anddischarge the same outwardly from said blades to thereby move meltingmedia and scrap from the upper portion to the lower portion of saidcharging bay so that said scrap will be mixed with said media to meltthe scrap for circulation through the system as part of said media. 13.An improved method of melting metal scrap in molten melting mediacomprising the steps of:(a) providing a body of molten melting media ina bay having a rotating impeller submerged in melting media therein withan upwardly-downwardly extending axis of rotation; (b) introducing metalscrap to said bay above said impeller; (c) introducing molten meltingmedia to an upper region of the bay above said impeller; and (d) meltingand moving the metal scrap by ingesting scrap and molten melting mediadownwardly in said bay by action of said impeller, said impeller havinga base member situated about said axis of rotation and transversethereto, an upper (top) member situated about and transverse to saidaxis of rotation and above said base member and spaced therefrom, saidupper (top) member having a central inlet opening therein, and bladesbetween said base and upper member, said blades extending inwardlytoward said axis and outwardly toward the periphery of said upper andbase members, the scrap and melting media substantially downwardlyentering said inlet opening in the upper impeller member and beingpropelled substantially transversely from between said base and uppermembers by said rotating impeller.
 14. An improved method of meltingmetal scrap in molten melting media comprising the steps of:(a)providing a body of molten melting media in a bay having a rotatingimpeller submerged in the melting media with an upwardly-downwardlyextending axis of rotation; (b) introducing metal scrap to said bayabove said impeller; (c) introducing a supply of molten melting media toan upper region of the bay above said impeller; (d) melting and movingthe metal scrap by ingesting scrap and molten melting media downwardlyin said bay by action of said impeller, said impeller having a basemember situated about said axis of rotation and transverse thereto, anupper (top) member situated about and transverse to said axis ofrotation and above said base member and spaced therefrom, said upper(top) member having a central inlet opening therein, and blades betweensaid base and upper member, said blades extending inwardly toward saidaxis and outwardly toward the periphery of said upper and base members,the scrap and melting media substantially downwardly entering said inletopening in the upper impeller member and being propelled substantiallytransversely from between said base and upper members by said rotatingimpeller; and (e) retarding recirculation within said charging bay ofmelting media propelled from said impeller back to said inlet opening insaid upper impeller member by means cooperating with said impeller insaid bay to retard such recirculation.
 15. An improved method of meltingmetal scrap in molten melting media comprising the steps of:(a)providing a body of molten melting media in a bay having a rotatingimpeller submerged in the melting media with an upwardly-downwardlyextending axis of rotation; (b) introducing metal scrap to said bayabove said impeller; (c) introducing a supply of molten melting media toan upper region of the bay above said impeller; (d) melting and movingthe metal scrap by ingesting scrap and molten melting media downwardlyin said bay by action of said impeller, said impeller having a basemember situated about said axis of rotation and transverse thereto, anupper (top) member situated about and transverse to said axis ofrotation and above said base member and spaced therefrom, said upper(top) member having a central inlet opening therein, and blades betweensaid base and upper member, said blades extending inwardly toward saidaxis and outwardly toward the periphery of said upper and base members,the scrap and melting media substantially downwardly entering said inletopening in the upper impeller member and being propelled substantiallytransversely from between said base and upper members by said rotatingimpeller; and (e) retarding recirculation within said charging bay ofmelting media propelled from said impeller back to said inlet opening insaid upper impeller member by means cooperating with said impeller insaid bay to retard such recirculation and to urge molten melting mediamoving through said impeller out of said bay.
 16. A recirculating systemfor melting metal scrap in molten media comprising:(a) a heating bay forheating molten media; (b) a scrap charging bay; (c) flow paths toprovide a loop for movement of molten media from said charging bay tosaid heating bay and from said heating bay to said charging bay; (d) animpeller positioned in said charging bay, said impeller having anupwardly-downwardly extending axis of rotation and having a base membersituated about said axis of rotation and transverse thereto, an upper(top) member situated about and transverse to said axis of rotation andabove said base member and spaced therefrom, said upper (top) memberhaving a central inlet opening therein, and blades between said base andupper member, said blades extending inwardly toward said axis andoutwardly toward the periphery of said upper and base members; (e) saidimpeller being positioned and arranged in said bay with respect to sitesfor introduction of molten metal and scrap such that rotation of saidimpeller ingests molten metal and scrap downwardly in said bay, thescrap and melting media substantially downwardly entering said inletopening in the upper impeller member and being propelled substantiallytransversely from between said base and upper member by said rotatingimpeller; and (f) means cooperating with said impeller in said chargingbay to retard recirculation within said charging bay of melting mediapropelled from said impeller back to said inlet opening in said upperimpeller member.
 17. The method in accordance with claim 13 includingmeans cooperating with said impeller in said charging bay for retardingrecirculation within said charging bay of melting media propelled fromsaid impeller back to said inlet opening in said upper impeller member.18. A recirculating system for melting metal scrap in molten mediacomprising:(a) a heating bay for heating molten media; (b) a scrapcharging bay; (c) flow paths to provide a loop for movement of moltenmedia from said charging bay to said heating bay and from said heatingbay to said charging bay; (d) an impeller positioned in said chargingbay, said impeller having an upwardly-downwardly extending axis ofrotation and having a base member situated about said axis of rotationand transverse thereto, an upper (top) member situated about andtransverse to said axis of rotation and above said base member andspaced therefrom, said upper (top) member having a central inlet openingtherein, and blades between said base and upper member, said bladesextending inwardly toward said axis and outwardly toward the peripheryof said upper and base members; (e) said impeller being positioned andarranged in said bay with respect to sites for introduction of moltenmetal and scrap such that rotation of said impeller ingests molten metaland scrap downwardly in said bay, the scrap and melting mediasubstantially downwardly entering said inlet opening in the upperimpeller member and being propelled substantially transversely frombetween said base and upper member by said rotating impeller; and (f)means cooperating with said impeller in said charging bay to retardrecirculation within said charging bay of melting media propelled fromsaid impeller back to said inlet opening in said upper impeller memberand to urge molten media propelled from said impeller out of saidcharging bay.
 19. The method according to claim 13 including meanscooperating with said impeller in said charging bay for retardingrecirculation within said charging bay of melting media propelled fromsaid impeller back to said inlet opening in said upper impeller memberand for urging molten media propelled from said impeller out of saidcharging bay.
 20. A recirculating system for melting metal scrap inmolten media comprising:(a) a heating bay for heating molten media; (b)a scrap charging bay; (c) flow paths to provide a loop for movement ofmolten media from said charging bay to said heating bay and from saidheating bay to said charging bay; (d) an impeller positioned in saidcharging bay, said impeller having an upwardly-downwardly extending axisof rotation and having a base member situated about said axis ofrotation and transverse thereto, an upper (top) member situated aboutand transverse to said axis of rotation and above said base member andspace therefrom, said upper (top) member having a central inlet openingtherein, and blades between said base and upper member, said bladesextending inwardly toward said axis and outwardly toward the peripheryof said upper and base members; (e) said impeller being positioned andarranged in said bay below the positions for introduction of moltenmetal and scrap and such that rotation of said impeller ingests moltenmetal and scrap downwardly in said bay, the scrap and melting mediasubstantially downwardly entering said inlet opening in the upperimpeller member and being propelled substantially transversely frombetween said base and upper member by said rotating impeller; and (f)means cooperating with said impeller in said charging bay to retardrecirculation within said charging bay of melting media propelled fromsaid impeller back to said inlet opening in said upper impeller memberand to urge molten media propelled from said impeller out of saidcharging bay.
 21. A recirculating system for melting metal scrap inmolten media comprising:(a) a heating bay for heating molten media; (b)a scrap charging bay; (c) flow paths to provide a loop for movement ofmolten media from said charging bay to said heating bay and from saidheating bay to said charging bay; (d) means for moving said mediathrough said loop from said charging bay to said heating bay and back;(e) an impeller positioned in said charging bay, said impeller having anupwardly-downwardly extending axis of rotation and having a base membersituated about said axis of rotation and transverse thereto, an upper(top) member situated about and transverse to said axis of rotation andabove said base member and spaced therefrom, said upper (top) memberhaving a central inlet opening therein, and blades between said base andupper member, said blades extending inwardly toward said axis andoutwardly toward the periphery of said upper and base members; (f) saidimpeller being positioned and arranged in said bay with respect to sitesfor introduction of molten metal and scrap such that rotation of saidimpeller ingests molten metal and scrap downwardly in said bay, thescrap and melting media substantially downwardly entering said inletopening in the upper impeller member and being propelled substantiallytransversely from between said base and upper member by said rotatingimpeller; and (g) means cooperating with said impeller in said chargingbay to retard recirculation within said charging bay of melting mediapropelled from said impeller back to said inlet opening in said upperimpeller member.
 22. The improvement according to claims 13, 14, 15 and16 wherein the inner portions of said impeller blades are offset fromthe impeller axis in the direction of rotation.
 23. The improvementaccording to claims 13, 14, 15 and 16 wherein the inner portions of saidimpeller blades are offset from the impeller axis in the direction ofrotation and the outer portions of said impeller blades curve backwardlyfrom the direction of rotation.
 24. The recirculating system accordingto claim 21 wherein said impeller discharge provides at least part ofsaid means for moving said media through said loop.
 25. Therecirculating system in accordance with claim 16 wherein said uppermember is a substantially flat ring member having a substantiallycircular opening therein.
 26. The recirculating system in accordancewith claim 16 wherein said base member is a circular member.
 27. Therecirculating system in accordance with claim 17 wherein said basemember has a centrally located hub thereon and wherein said bladesextend from said hub in a generally radial direction.
 28. Therecirculating system in accordance with claim 27 wherein said blades arecurved backwardly from the direction of rotation and extend from saidhub towards the circumference of said base member.
 29. The recirculatingsystem in accordance with claim 1 wherein said impeller has a centralhub and said blades extend outwardly from said hub but eccentric to itsaxis in the direction of rotation and curve backwardly from thedirection of rotation.
 30. An improved recirculatory method for meltingscrap metal comprising:(a) circulating molten melting media from acharging bay through a flow path to a heating bay for heating said mediaand back through a flow path to said charging bay; (b) rotating animpeller in said charging bay, said impeller having anupwardly-downwardly axis of rotation; (c) introducing metal scrap tosaid bay above said impeller; (d) introducing molten melting media to anupper region of the bay above said impeller; (e) melting and moving themetal scrap by ingesting scrap and molten melting media downwardly insaid bay by action of said impeller, said impeller having a base membersituated about said axis of rotation and transverse thereto, an upper(top) member situated about and transverse to said axis of rotation andabove said base member and spaced therefrom, said upper (top) memberhaving a central inlet opening therein, and blades between said base andupper member, said blades extending inwardly toward said axis andoutwardly toward the periphery of said upper and base members, the scrapand melting media substantially downwardly entering said inlet openingin the upper impeller member and being propelled substantiallytransversely from between said base and upper members by said rotatingimpeller.
 31. An improved recirculatory method for melting scrap metalcomprising:(a) circulating molten melting media from a charging baythrough a flow path to a heating bay for heating said media and backthrough a flow path to said charging bay; (b) rotating an impeller insaid charging bay, said impeller having an upwardly-downwardly axis ofrotation; (c) introducing metal scrap to said bay above said impeller;(d) introducing molten melting media to an upper region of the bay abovesaid impeller; (e) melting and moving the metal scrap by ingesting scrapand molten melting media downwardly in said bay by action of saidimpeller, said impeller having a base member situated about said axis ofrotation and transverse thereto, an upper (top) member situated aboutand transverse to said axis of rotation and above said base member andspaced therefrom, said upper (top) member having a central inlet openingtherein, and blades between said base and upper member, said bladesextending inwardly toward said axis and outwardly toward the peripheryof said upper and base members, the scrap and melting mediasubstantially downwardly entering said inlet opening in the upperimpeller member and being propelled substantially transversely frombetween said base and upper members by said rotating impeller; and (f)retarding recirculation within said charging bay of melting mediapropelled from said impeller back to said inlet opening in said upperimpeller member by means cooperating with said impeller in said bay toretard such recirculation and urge molten melting media moving throughsaid impeller out of said bay.